[qemu.git] / docs / specs / standard-vga.txt


QEMU Standard VGA
=================

Exists in two variants, for isa and pci.

command line switches:
    -vga std            [ picks isa for -M isapc, otherwise pci ]
    -device VGA         [ pci variant ]
    -device isa-vga     [ isa variant ]


PCI spec
--------

Applies to the pci variant only for obvious reasons.

PCI ID: 1234:1111

PCI Region 0:
   Framebuffer memory, 16 MB in size (by default).
   Size is tunable via vga_mem_mb property.

PCI Region 1:
   Reserved (so we have the option to make the framebuffer bar 64bit).

PCI Region 2:
   MMIO bar, 4096 bytes in size (qemu 1.3+)

PCI ROM Region:
   Holds the vgabios (qemu 0.14+).


IO ports used
-------------

03c0 - 03df : standard vga ports
01ce        : bochs vbe interface index port
01cf        : bochs vbe interface data port (x86 only)
01d0        : bochs vbe interface data port


Memory regions used
-------------------

0xe0000000 : Framebuffer memory, isa variant only.

The pci variant used to mirror the framebuffer bar here, qemu 0.14+
stops doing that (except when in -M pc-$old compat mode).


MMIO area spec
--------------

Likewise applies to the pci variant only for obvious reasons.

0000 - 03ff : reserved, for possible virtio extension.
0400 - 041f : vga ioports (0x3c0 -> 0x3df), remapped 1:1.
              word access is supported, bytes are written
              in little endia order (aka index port first),
              so indexed registers can be updated with a
              single mmio write (and thus only one vmexit).
0500 - 0515 : bochs dispi interface registers, mapped flat
              without index/data ports.  Use (index << 1)
              as offset for (16bit) register access.
Commit	Line	Data
cc228248 GH	1
	2	QEMU Standard VGA
	3	=================
	4
	5	Exists in two variants, for isa and pci.
	6
	7	command line switches:
	8	-vga std [ picks isa for -M isapc, otherwise pci ]
	9	-device VGA [ pci variant ]
	10	-device isa-vga [ isa variant ]
	11
	12
	13	PCI spec
	14	--------
	15
	16	Applies to the pci variant only for obvious reasons.
	17
	18	PCI ID: 1234:1111
	19
	20	PCI Region 0:
	21	Framebuffer memory, 16 MB in size (by default).
	22	Size is tunable via vga_mem_mb property.
	23
	24	PCI Region 1:
	25	Reserved (so we have the option to make the framebuffer bar 64bit).
	26
	27	PCI Region 2:
	28	MMIO bar, 4096 bytes in size (qemu 1.3+)
	29
	30	PCI ROM Region:
	31	Holds the vgabios (qemu 0.14+).
	32
	33
	34	IO ports used
	35	-------------
	36
	37	03c0 - 03df : standard vga ports
	38	01ce : bochs vbe interface index port
df9ffb72 GH	39	01cf : bochs vbe interface data port (x86 only)
df9ffb72 GH	40	01d0 : bochs vbe interface data port
cc228248 GH	41
	42
	43	Memory regions used
	44	-------------------
	45
	46	0xe0000000 : Framebuffer memory, isa variant only.
	47
	48	The pci variant used to mirror the framebuffer bar here, qemu 0.14+
	49	stops doing that (except when in -M pc-$old compat mode).
	50
	51
	52	MMIO area spec
	53	--------------
	54
	55	Likewise applies to the pci variant only for obvious reasons.
	56
	57	0000 - 03ff : reserved, for possible virtio extension.
	58	0400 - 041f : vga ioports (0x3c0 -> 0x3df), remapped 1:1.
	59	word access is supported, bytes are written
	60	in little endia order (aka index port first),
	61	so indexed registers can be updated with a
	62	single mmio write (and thus only one vmexit).
	63	0500 - 0515 : bochs dispi interface registers, mapped flat
	64	without index/data ports. Use (index << 1)
	65	as offset for (16bit) register access.